Endoscopic ultrasound-guided fiducial marker placement in pancreatic cancer:A systematic review and meta-analysis

BACKGROUND Pancreatic cancer(PC)mortality remains high despite advances in therapy.Combination chemoradiotherapy offers modest survival benefit over monotherapy with either.Fiducial markers serve as needed landmarks for imageguided radiotherapy(IGRT).Traditionally,these markers were placed surgically or percutaneously with limitations of each.Endoscopic ultrasound-guided placement overcomes these limitations.AIM To evaluate the safety,efficacy,and feasibility of endoscopic ultrasound(EUS)-guided fiducial placement for PC undergoing IGRT.METHODS Articles were searched in MEDLINE,PubMed,and Ovid journals.Pooling was conducted by fixed and random effects models.Heterogeneity was assessed using Cochran’s Q test based upon inverse variance weights.RESULTS Initial search identified 1024 reference articles for EUS-guided fiducial placement in PC.Of these,261 relevant articles were reviewed.Data was extracted from 11 studies(n=820)meeting inclusion criteria.Pooled proportion of successful placement was 96.27%(95%CI:95.35-97.81)with fiducial migration rates low at 4.33%(95%CI:2.45-6.71).Adverse event rates remained low,with overall pooled proportion of 4.85%(95%CI:3.04-7.03).CONCLUSION EUS-guided placement of fiducial markers for IGRT of PC is safe,feasible,and efficacious.The ability to target deep structures under direct visualization while remaining minimally invasive are added benefits.Moreover,the ability to perform fine needle aspiration or celiac plexus neurolysis add value and increase patient-care efficiency.Whether EUS-guided fiducial placement improves outcomes in IGRT or offers any mortality benefits over traditional placement remains unknown and future studies are needed.

Endoscopic ultrasound-guided fiducial marker placement for neoadjuvant chemoradiation therapy for resectable pancreatic cancer

BACKGROUND Preoperative neoadjuvant chemoradiation therapy(NACRT)is applied for resectable pancreatic cancer(RPC).To maximize the efficacy of NACRT,it is essential to ensure the accurate placement of fiducial markers for image-guided radiation.However,no standard method for delivering fiducial markers has been established to date,and the nature of RPC during NACRT remains unclear.AIM To determine the feasibility,safety and benefits of endoscopic ultrasound-guided(EUS)fiducial marker placement in patients with RPC.METHODS This was a prospective case series of 29 patients(mean age,67.5 years;62.1%male)with RPC referred to our facility for NACRT.Under EUS guidance,a single gold marker was placed into the tumor using either a 19-or 22-gauge fine-needle aspiration needle.The differences in daily marker positioning were measured by comparing simulation computed tomography and treatment computed tomography.RESULTS In all 29 patients(100%)who underwent EUS fiducial marker placement,fiducials were placed successfully with only minor,self-limiting bleeding during puncture observed in 2 patients(6.9%).NACRT was subsequently administered to all patients and completed in 28/29(96.6%)cases,with one patient experiencing repeat cholangitis.Spontaneous migration of gold markers was observed in 1 patient.Twenty-four patients(82.8%)had surgery with 91.7%(22/24)R0 resection,and two patients experienced complete remission.No inflammatory changes around the marker were observed in the surgical specimen.The daily position of gold markers showed large positional changes,particularly in the superior-inferior direction.Moreover,tumor location was affected by food and fluid intake as well as bowel gas,which changes daily.CONCLUSION EUS fiducial marker placement following NACRT for RPC is feasible and safe.The RPC is mobile and is affected by not only aspiration,but also food and fluid intake and bowel condition.

Fusion of Absolute and Recursive Information to Overcome Jitter and Occlusion in ARToolKit System

According to the most mature marker based augmented reality system ARToolKit only utilizes absolute information in pose estimation, a novel technique is presented in this paper. The proposed method embeds the recursive information as well to make ARToolKit system smoother by eliminating the jitter and more robust to occlusion conditions. Experiments on the jitter improvement has been performed, the results show that the proposed method is very effective.

Hepatocellular carcinoma effective stereotactic body radiotherapy using Gold Anchor and the Synchrony system:Two case reports and review of literature

BACKGROUND Radiotherapy for hepatocellular carcinoma(HCC)is considered to have limited efficacy because of treatment intensity considering that the irradiated area includes the liver,which is highly radiosensitive.In this report,we present two cases in which tumor control by surgical resection,radiofrequency ablation,transcatheter arterial chemoembolization(TACE),and lenvatinib administration was difficult,but stereotactic body radiotherapy(SBRT)using the Synchrony system by Radixact?and Gold Anchor?(GA)was effective.CASE SUMMARY A 60-year-old man had a single 10-cm HCC in the right lobe.Viable lesions remained after TACE,and levels of alpha-fetoprotein and protein induced by vitamin K antagonists II(PIVKA-II)decreased and quickly re-elevated.We performed SBRT with GA.Three weeks after implantation,localized radiotherapy(SBRT;40 Gy/5 fractions)was performed using the Synchrony system by Radixact?.Four weeks later,the viable lesion had disappeared,and the PIVKA-II levels decreased.A 77-year-old man had a single 12-cm HCC in the right lobe.The patient experienced recurrence after hepatectomy.Further recurrence occurred after TACE,and we performed SBRT with GA.Because of the proximity of the HCC to the gastrointestinal tract,localized radiotherapy(SBRT;39 Gy/13 fractions)to the HCC was performed 3 wk after implantation using the Synchrony system by Radixact?.Four weeks later,the viable lesion had disappeared on computed tomography,and the PIVKA-Ⅱlevels decreased.CONCLUSION SBRT using the Synchrony system and GA can deliver a large dose accurately and safely,and could have a high therapeutic effect.

Fiducial Marker Based on Projective Invariant for Augmented Reality

Fiducial marker based Augmented Reality has many applications. So far the inner pattern of the fiducial marker is always used to encode the markers. Thus a large portion of the fiducial marker image is used for encoding instead of providing corresponding feature points for pose accuracy. This paper presents a novel method which utilizes directly the projective invariant contained in the positional relation of the corresponding feature points to encode the marker. Tile proposed method does not require the region of pattern image for encoding any more and can provide more corresponding feature points so that higher pose accuracy can be achieved easily. Many related approaches such as cumulative distribution function, reprojection verification and robust process are proposed to overcome the problem of sensibility of the projective invariant. Experimental results show that the proposed fiducial marker system is reliable and robust, and can provide higher pose accuracy than that achieved by existing fiducial marker systems.